PLATE IV. 
Fig, 1, Tnrbinated madreporite, possessing somewhat of a pyramidal form : remains of 
its radicle being observable around its lower parts. 
2. A fossil of the same species; but more of a discoidal form. 
3. Another fossil of the same species ; at the lower part of which, traces of the root- 
like projections are also observable. About the middle of the coral a cleft 
divides it through about half its diameter : the coral-forming insect having 
there partly finished his labours and began them a-new. 
4. The stellated surface of a madreporite, bearing a very peculiar form. 
5. A turbinated madreporite, somewhat resembling Madrepora Cyathus. Linn. 
6. The shirt-button madreporite, ( Madrepora PorpitaJ Linn. 
7 . A turbinated madreporite, the external coat of which having been removed, the 
disposition of its perpendicular lamellae is displayed. 
8. A section of an elongated turbinated madreporite : displaying its transverse and 
longitudinal lamellre. 
9. A simple madreporite, bearing the form of a compressed cone. 
10. A turbinated madreporite from Gothland : its disk bearing very much the appear- 
ance of the porpital madreporite. 
11. A turbinated madreporite, apparently of the same species with the former, but of 
a more conical shape. Fossils resembling this and the preceding specimen 
are, I believe, frequently found in the island of Sheppy. 
12. Is a cast of calcareous spar, formed in the vacuities of a turbinated madrepore : 
the remains of the animal having been removed by decomposition. 
13 and 14. Two transverse polished sections of a large turbinated madreporite of the 
species at Fig. 8. The section, Fig, 14, made near to the pedicle, is seen to 
possess much fewer laminae than the section Fig. 13, which was made where 
the coral had obtained its full thickness. 
15. A delicately formed turbinated madreporite found in chalk. 
16. A fossil of the same species in chalk. In this specimen the mode of attachment 
peculiar to these animals is shewn, the pedicle of the madreporite being adhe- 
rent to the shell of an echinus. 
17. Is the section of a piece of Blankenburg marble, in which is imbedded a turbinated 
madrepore of the species represented. Fig. 1, 2, and 3. 
